QUETTA, Pakistan (AP) — Gunmen killed six people in a pair of attacks in southwest Pakistan on Thursday, one of which targeted local employees of the United Nations Food and Agriculture Organization, officials said.

The gunmen opened fire on the U.N. staff as they were riding in a car through Baluchistan province’s Mastung district, killing two people, said police officer Rustam Khan.

The two killed included a member of the group’s project staff and a hired driver, said a U.N. official, speaking on condition of anonymity because he was not authorized to talk to the media. Another staff member was wounded, he said.

No group has claimed responsibility for the attack.

Baluchistan has experienced a decades-long insurgency by nationalists who demand greater autonomy and a larger share of the province’s natural resources. Baluch nationalists have targeted Pakistani security forces and officials in the past, as well as aid workers helping the government.

The province is also home to many Taliban militants, allegedly including the group’s leader, Mullah Omar.

Earlier Thursday, gunmen on motorcycles opened fire on a passenger van in Quetta, the capital of Baluchistan province, killing four Shiite Muslims in an apparent sectarian attack, said police officer Shaukat Khan.

Sunni militants with links to al-Qaida and the Taliban have carried out scores of bombings and shootings across the country against minority Shiites in recent years, especially in Baluchistan.

The Sunni-Shiite schism over the true heir to Islam’s Prophet Muhammad dates back to the seventh century.